You need to own the server you're trying to add the bot to or at least have the Manage Server permission. Another reason might be that you're logged in to the wrong account on the browser. Go to https://discordapp.com/channels/@me on your browser and log out then log in again.
KDA is another variation of KDR, which is your kills to deaths ratio. So your KDA is your kills and assists to deaths ratio.
In PaladinsGeek we calculate the KDA acccording to this equation: KDA = (Kills + 0.5 * Assists) / Deaths
It's either the wrong platform, or your account is below level 5. Supported platforms are PC, Xbox, Switch and PS4.